Rachio detected a fault in zone master valve with a motorized ball valve

I installed a US Solid motorized ball valve (9~24V AC/DC) before the backflow preventer as my master valve.

Half of the time, it fails with message Rachio detected a fault in zone master valve while running a schedule on your controller, so basically, my irrigation system is so unreliable and I can not trust it.

How do I do some debugging? Thanks.

Is it possible that valve draws more current than the Rachio can supply?

Rachio (or probably any sprinkler clock) can’t fire that type of valve. The master valve is meant to be a secondary solenoid style valve. I suspect the 3-5 second open/close time might be causing the fault, but can’t say for sure.

US Solid makes solenoid style valves as well, but you can do it quite a bit cheaper with a standard irrigation valve.

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@dbtsai - one option would be to put a SPST 24 VAC relay and additional 24 VAC power supply in the system. Have Rachio fire the relay, which should have a low draw for its coil, and the connect the additional power supply through the relay to the motorized ball valve.

If you want to check that it is the ball valve causing the issue, then I’d do one of two test.

  1. If there is a terminal with no valve connected to it, configure that zone as an active zone and then fire off a quick run, 5 minutes. If there is an error message, then the ball valve is pulling too much current. If all the terminals are in use, then one can remove the field wire for this test.

  2. Run a quick run, say 5 minutes, on a zone that is not at the start of a schedule - in the event that the first zone being called is actually causing the problem. If there is not error, then run the first zone and see if you get an error message. If so, then it might be the first zone’s solenoid that is pulling too much current.

When there is a master valve in the system, Rachio has to guess if it is the master valve or the zone valve that is causing the problem.

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Hello! I have the exact same issue, very sporadic, it will work 50% of the time. I tried checking the US solid valve by attaching it to a 9 V battery and it does open correctly systematically with the battery. When it is wired to the Rachio3, it fails one time out of Two. I have three of these US solid goalies, so I don’t think it is an issue with a the valve been defective…
Can anyone help ?

Not sure what type of valve you are using, as US Solid has a number of styles, but there is a chance Rachio doesn’t have the power to run some of those. The master valves are typically just another plastic solenoid zone valve wired in ahead of the other valves.

Hello! I have the exact same issue, very sporadic, it will work 50% of the time. the current is 0.2 amps, what is the issue?

I’m using 3 of these US Solid motorized ball valves as well. They are the 2-wire, auto-close model, which is the model that should work with a sprinkler timer. I’m alao getting zone faults for all 3 of them. The valves consume 5 watts, which is similar to a solenoid. My guess is the issue is they use too little current once they are open which could be interpreted as a broken wire. It takes 3 to 5 seconds to open. Once open, the valve consumes very little power. When power is removed, the valve closes using power stored in a capacitor inside the valve.

I spoke with tech support and verified that the rachio controller is looking for a minimum current draw. The US Solid ball valve is drawing less current than a solenoid, and once the valve is open, it draws very little current.

As a work around I put an 820 ohm 2 watt resistor in parallel with the valve at the valve end of the wire. This would draw about 30-35 ma - much less than a solenoid, but enough to pass the fault test. (More than 1k ohm didn’t work. Lower values could work but would draw more current) This made the faults go away. Ofcourse if the valve failed, it would not be detected, but a break in the wire would.

Which exact model have you bought?
5 watts @ 24VAC provided by Rachio means 200mA current draw, plenty for a normal measurement of any valve. Rachio can drive pump start relays which, when properly sized, consume less than 50mA.

If the fault is occurring after the valve is activated (and goes to low power), than you may be right about the current draw being below the threshold and being detected by Rachio as valve fault. Resistor may be a good solution.

The US Solid specs says 5 watts, but it only draws current while opening, 3-5 seconds. After that it draws very little current - just enough to sense the signal to stay open. When the signal is gone, it uses the current from an internal capacitor to close the valve. The zone fault is detected after the valve is open, and the measured current is very low.

To get around this fault detection, I’m using a 100 ohm, 5 watt resistor in parallel with the valve. I started with a 800 ohm, but faults were still being detected.

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I have success installed 50 Ohm 10W resistor is series with US Solid ball valve 9-24 AC/DC. I tried solution by Thinkpeace, but 100 Ohm in parallel didn’t work for me at all, probably Thinkpeace has different type of ball valve than I have. I suggest use series other than parallel, it is better for power consumption and will not make resistor hot, because when ball valve is opened, current though the circuit is very low.

Upd. 25 Ohm resistor in series with ball valve works better, more power to the valve, so it opens faster. No fault zone anymore.

Hi, can you pls share what exactly resistor did you used that helped you solve the issue? tk smuch

attach serial to ball valve (not parallel!)

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Using a resistor as a surge suppressor, nice :slight_smile:

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Tks Yura.

Gene, can you plus expand on your comment? Is this a good solution from Rachio perspective?


Ball valves can’t operate on AC voltage, they have capacitors which need to be charged to provide a DC voltage to the motor turning the valve. When capacitor is discharged, it takes a lot of current initially to charge it, this is called “surge current” as there is a big spike at first before things settle down.

Unfortunately, the surge current can be a high as a short circuit (whereas the zone wire is directly connected to the commons, causing the maximum current flow). Rachio protects itself from short circuits by cutting off the zone as soon as possible, otherwise the fuse would trip and cause the whole controller to shut down.

Adding the resistor in series with the ball valve limits the surge current to a value that Rachio does not detect as a short circuit.

Depending on the ball valve, you may have a different issue down the line, whereas the current draw of the valve drops to a low enough value that Rachio thinks that the valve has completely failed. In which case you’ll need a second resistor parallel with the valve. This happens because ball valves use energy only while activating (deactivation is usually handled by the mechanical energy stored in the spring). Once active the current / power draw of the ball valve drops to near zero, as if the valve was not there at all.

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thanks Gene for the info as always. Very clear your description, I am sure my valve is drawing more current as the zone immediately fails once selected. will report back findings after trying the resistor approach.

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I’m considering to add a “Master Valve” using the “US Solid” and I’m wondering if I still need to use the resistor or if this previous mentioned issue was correct on the current FW version.

Any feedback would be appreciated.